<template>
    <canvas id="canvas" :width="width" :height="height" @click="handleShowNUm"></canvas> 
</template>

<script>
    export default {
        props:{
            handleCanvasCode:Function,
            width:Number,
            height:Number
        },
        data(){
            return{
                show_num:[]
            }
        },
        methods:{
            // 获取随机颜色
            randomColor() {
                let r = Math.floor(Math.random() * 256);
                let g = Math.floor(Math.random() * 256);
                let b = Math.floor(Math.random() * 256);
                return "rgb(" + r + "," + g + "," + b + ")";
            },
            
            // 绘制验证码
            draw() {
                let canvas_width = document.getElementById("canvas").width;
                let canvas_height = document.getElementById("canvas").height;
                let canvas = document.getElementById("canvas"); //获取到canvas的对象，演员
                let context = canvas.getContext("2d"); //获取到canvas画图的环境，演员表演的舞台
                canvas.width = canvas_width;
                canvas.height = canvas_height;
                let sCode = "A,B,C,E,F,G,H,J,K,L,M,N,O,P,Q,R,S,T,U,V,W,X,Y,Z,1,2,3,4,5,6,7,8,9,0";
                let aCode = sCode.split(",");
                let aLength = aCode.length; //获取到数组的长度

                for (let i = 0; i <= 3; i++) {
                    let j = Math.floor(Math.random() * aLength); //获取到随机的索引值
                    let deg = Math.random() * 30 * Math.PI / 180; //产生0~30之间的随机弧度
                    let txt = aCode[j]; //得到随机的一个内容
                    this.show_num[i] = txt.toLowerCase();
                    let x = 10 + i * 20; //文字在canvas上的x坐标
                    let y = 20 + Math.random() * 8; //文字在canvas上的y坐标
                    context.font = "bold 23px 微软雅黑";

                    context.translate(x, y);
                    context.rotate(deg);

                    context.fillStyle = this.randomColor();
                    context.fillText(txt, 0, 0);

                    context.rotate(-deg);
                    context.translate(-x, -y);
                }
                for (let i = 0; i <= 5; i++) { //验证码上显示线条
                    context.strokeStyle = this.randomColor();
                    context.beginPath();
                    context.moveTo(Math.random() * canvas_width, Math.random() * canvas_height);
                    context.lineTo(Math.random() * canvas_width, Math.random() * canvas_height);
                    context.stroke();
                }
                for (let i = 0; i <= 30; i++) { //验证码上显示小点
                    context.strokeStyle = this.randomColor();
                    context.beginPath();
                    let x = Math.random() * canvas_width;
                    let y = Math.random() * canvas_height;
                    context.moveTo(x, y);
                    context.lineTo(x + 1, y + 1);
                    context.stroke();
                }
                this.handleCanvasCode(this.show_num.join(''))
            },

            // 切换验证码
            handleShowNUm(){
                this.draw()
            }
        },
        mounted(){
            this.draw()
        }
    }
</script>

<style lang="scss" scoped>

</style>